Question: Simplify the following expression: $\sqrt{80} - \sqrt{20}$
Answer: First, try to factor any perfect squares out of the radicals. $= \sqrt{80} - \sqrt{20}$ $= \sqrt{16 \cdot 5} - \sqrt{4 \cdot 5}$ Separate the radicals and simplify. $= \sqrt{16} \cdot \sqrt{5} - \sqrt{4} \cdot \sqrt{5}$ $= 4\sqrt{5} - 2\sqrt{5}$ Finally, simplify by combining the terms. $= ( 4 - 2 )\sqrt{5} = 2\sqrt{5}$